public void Push(string value)
{
var item = new StackItem(value);
item.Next = _head;
_head = item;
Count++;
}
public string Pop()
{
if (_head == null)
return null;
var result = _head.Value;
_head = _head.Next;
Count--;
return result;
}
public Stack()
{
_head = null;
Count = 0;
}